Especially for automatic milking apparatus it is advantageous if the opening of a milking cup can be widened when applying the cup.
Known from EP-A-347004, FIG. 1 thereof, is a milking cup with a variable diameter for a teat of, for instance, a cow, which is of particular importance with devices for automatic arranging of such milking cups, since it is easier to place the teat in an opening of greater diameter. During milking, a good seal from the outside environment of the vacuum to be generated in the inner space of the milking cup has to be ensured. This prior art cup has a rest position in which the opening is wide, and a force is exerted to a ring which clamps onto the teat and provides sealing from the outside environment. Such clamping is however undesirable, as this discomforts the animal. Further, it is to be expected that the ring will not be circular in its wide position, which is also undesirable.
In FIG. 2, 3 from EP-A-347004 a teat catcher having a narrow rest position is shown. This teat catcher is however operated by means of cables. The attachment of cables to the rubbery material is very difficult: the rubbery material will have to be reinforced and/or the rubbery material will not endure the forces from the cables. Further, cables from different cups of a milking set will interfere with one another.